The pressure swelling in her head often led to vomiting and confusion. Eight of McMillan's part-time employees at Video Star in Ayer also suffered from frequent headaches. Her husband Frederick, and 12-year-old son, Tyler, were affected, too. For two years,workers at the West Main Street business got used to swallowing Advil and chalked up the experience to “the stress” of working in retail.

“Nobody knew any better,” McMillan said. “It became a running joke after a while, how hundreds of Advil tablets would disappear in no time.”

In March 2004, a few men pulled up in a truck hauling large rolls of plastic. Soaring levels of toxic vapors prompted the state Department of Environmental Protection to order an immediate shutdown of Video Star and overnight, the McMillans lost their livelihood.

“No one ever told us we were sitting right on top of hazardous waste,” McMillan said. “For two years we were breathing it in everyday, and the landlord never said a word.”

According to the law, the McMillans' landlord didn't have to. Property owners are not required to tell renters about environmental hazards existing around a building. Rallying the support of local legislators, McMillan, a registered nurse and now a member of the Ayer Board of Health, is lobbying to protect a renter's right to know.

Yesterday, McMillan strolled the halls of UMass Lowell's Toxic Use Reduction Institute (TURI). By her side were some heavy environmental hitters, including her lawyer, Jan Schlictmann. Schlictmann gained fame following his representation of Woburn families in a class-action lawsuit against corporations that allegedly contaminated drinking water by illegally dumping industrial solvents. The Woburn story was retold in Jonathan Harr's best seller, A Civil Action, which was later turned into a movie starring John Travolta as Schlictmann.

“Unfortunately, it's the tragedies that lead to change,” Schlictmann said. “Right now there is no rule or law that makes property owners accountable for providing information about the land around a building. Hopefully Marilyn's experience will help bring insight into a system that is not working.”

Unless the public learns about the chemical stew it's basking in, Schlictmann fears the lives of many will be at risk.

Standing inside one of TURI's labs, a small audience scanned shelves stocked with household cleaners and degreasers. From shampoos and carpet cleaner to children's toys and dry cleaning, TURI reports thousands of consumer products are creating a deluge of hazardous chemical exposure. Last year, the research unit was commissioned by the state to research alternatives to five commonly used hazardous chemicals.

“In an ideal world, there would be many safe choices,” said Carole LeBlanc, laboratory director. “But the lack of push from the federal government has lead to the consequences of this current vacuum. Nothing mandates a consumer's right to know.”

The problem, according to experts, is evident in the country's unprecedented cancer numbers, and other rising diseases, especially in children.

For Donna Robbins, another supporter in McMillan's corner yesterday, the latter statistic is a heartbreaking reality.

Robbins' 9-year-old son, Robbie, died from leukemia in 1981. He was among the cluster of cancer cases in Woburn, which Robbins is certain were caused from drinking and bathing in water poisoned by toxic chemicals.

“I think it would have been great if we had (TURI) around when Woburn was in its beginning stages with everything,” Robbins said. “I'm afraid there are many Woburns in the world yet to be discovered. I hope when people learn about all the chemicals they're consuming, it helps change things in the future.”

McMillan is ready to take her battle to Beacon Hill. She is armed with a trail of letters and documents detailing correspondence between her landlord, LeMac Realty Trust, environmental engineers, the DEP and neighboring businesses.

Prior to LeMac's purchase of 211 Main St. in 1989, the commercial space was occupied by two separate dry-cleaning businesses. More than a decade of soil, water and air tests performed on and around the LeMac property show continuous elevated levels of the chemical perchloroephylene (PCE) ߞ; a solvent commonly used in dry cleaning. Soil samples taken outside Video Star revealed more than 2 million micrograms of PCE per cubic meter. The DEP's regulation is five. According to the DEP, the chemical is a known carcinogen that can target the nervous system, brain, kidneys and liver.

Renee LaFleur, co-owner of LeMac Realty Trust, said the company had no knowledge about the land's toxic history.

“We were just as surprised as she was,” LaFleur said. “We didn't know anything was there.”

LaFleur said the property is being cleaned and “expects it to be finished soon.”

But the McMillans, having sunk $300,000 in medical bills, legal fees and profit losses, aren't satisfied with LeMac's answers. Next week the activist is meeting with state Sen. Pamela Resor, D-Acton, to further fuel her efforts.

“There's no excuse for keeping people in the dark,” Schlictmann said. “It's a race between education and the ignorance that is killing us. It would be far less of an investment to get us smart, than it is to make us stupid.”